I’ve been having a random over heating problem for a bout a year now. It’s on my 5.8. Every single cooling part on my truck is 1.5 years old or newer minus heater core hoses and intake coolant hoses. I’ve tried two different thermostats. First I had a 165 now I’ve got a 195 , no change except the truck generally runs a little warmer.
The truck Will idle no problem in drive thrus or stop and go traffic but then out of now where over heat. Even on the highway in the winter (-20c) and usually cab heat goes away too. Yesterday it did this to me twice. The first time was in the city and then the truck wouldn’t start after (barley turned over) . I’m hopping that’s a separate issue. Then it did it on my way home, 60 km out of the city at 95km/hr. The gauge was at the “L” or all the way over to hot. It would fluctuate between the two. Then when I got it home while it was still running I grabbed my garden hose and sprayed the rad. It was extremely hot but this cooled th truck down very quickly. First the upper road hose started jumping or shaking then both upper and lower hoses collapsed and all the coolant got sucked out of the reservoir. And the truck ran fine on it’s own after
​​​​​​ sorry for the long story but I’m at my wits end here. I’m thinking cracked head or plugged rad. I’ve done a few flushes allready. The top end of the motor is brand new and the trucks got a 16” electric fan

Well I ripped everything apart today minus the water pump and I found a lot of sediment in my rad. Probably over a hand full came out. And that’s just what I dug out by hand never mind what my garden hose flushed out.
I have a fail safe thermostat and it did it’s job it was pined wide open and stuck there. I’m going to put ITV all back together tomorrow and run it with some distilled water and dump it and refill properly. I’m also going to try to make a temporary filter for the upper rad hose to catch what ever else is stuck in there.

I tried attaching some pictures but it’s not working

Yeah I gave it a pretty aggressive flush a few months ago and I think that loosens things up. I’m going to put it together tonight and flush it with distilled water. I tried to drain the block but I stripped the bolt. I might try again tonight to get it off

She’s running good today. Lots of cab heat but it’s cool when it’s set to windshield defrost??? But other then that it’s working great. I’ll dump the water tomorrow and maybe pull the rad again to flush it some more.